Forum Moderators: open
Basically the logic behind this was users often didn't notice the extra W and would bring in more traffic, other things like using wvvw.example.com where common.
Now some of the WWWW will be left over spam, other are due to servers being setup incorrectly and allowing any sub-domain to resolve the website content and yes users and links sometimes end up going to wwww.example.com a quick search for wwww.google.com brought back 12,900 results.
The other reason could simply be the website wanted to use WWWW as a sub-domain, or a they offer members sub-domains matching their ID's and someone user name is WWWW.